Add theme key for selected line number

Adds `ui.linenr.selected` which controls highlight of linu numbes which
have cursors on.

- Fallback to linenr if linenr.selected is missing

- Update docs and themes

- Add TODOs for themes with temporary linenr.selected

1 files changed, 5 insertions, 3 deletions

diff --git a/helix-view/src/theme.rs b/helix-view/src/theme.rs
index efb6a1af..51a21421 100644
--- a/helix-view/src/theme.rs
+++ b/helix-view/src/theme.rs
@@ -200,12 +200,14 @@ fn parse_modifier(value: &Value) -> Option<Modifier> {
 
 impl Theme {
     pub fn get(&self, scope: &str) -> Style {
-        self.styles
-            .get(scope)
-            .copied()
+        self.try_get(scope)
             .unwrap_or_else(|| Style::default().fg(Color::Rgb(0, 0, 255)))
     }
 
+    pub fn try_get(&self, scope: &str) -> Option<Style> {
+        self.styles.get(scope).copied()
+    }
+
     #[inline]
     pub fn scopes(&self) -> &[String] {
         &self.scopes